Evaluation of cyclic fatigue behavior of RACE EVO rotary Files: In-vitro comparative study.

Introduction: Comparative evaluation of the newly introduced; RACE EVO file system to the currently well-performing file systems like HyFlex EDM OneFile, Vortex Blue, ProTaper Gold (PTG) with regards to the cyclic fatigue resistance. Materials: &Methods.The endodontic rotary files under evaluation were segregated into four groups as follows:; RACE EVO, PTG, Vortex Blue, and HyFlex EDM OneFile. A detailed physical analysis of the cyclic fatigue resistance was performed in 15 files of each type (n = 60). Under the test conditions of 37 °C the test samples were subjected to continuous motion at the manufacturer recommended speed within an artificial curved canal until it fractured. For all the test samples, with the recording of time of fracture, calculation was done for number of cycles to fracture (NCF). In addition, the length of the fractured segment was determined. The fractured surface was further evaluated with scanning electron microscopic (SEM) images. Results: Highest significance for NCF was seen in HyFlex EDM OneFile followed by the Vortex Blue, PTG, and; RACE EVO (p < 0.05) by analyzing the data statistically. Significant differences among the lengths of the fractured segments were evident among tested files, ranging between 4.73 and 6.3 mm (p < 0.05) with HyFlex EDM OneFile uniquely differentiating from the others showing the fracture at 6.3 mm. The common features of cyclic fatigue failure was further substantiated by SEM images. Conclusions: Compared to the HyFlex EDM OneFile, Vortex Blue, and PTG files; RACE EVO demonstrated significantly lower resistance to cyclic fatigue.

Effect of NaOCl and EDTA irrigating solutions on the cyclic fatigue resistance of EdgeTaper Platinum instruments.

BACKGROUND: To compare the solution on the cyclic fatigue resistance of EdgeTaper Platinum (ETP) instruments with that of ProTaper Gold (PTG) in the presence of ethylenediaminetetraacetic acid (EDTA) or sodium hypochlorite (NaOCl) irrigating solutions. METHODS: Sixty PTG and 60 ETP instruments with the same size (#25) and taper (8%) were tested under 17% EDTA, 5.25% NaOCl, or distilled water (n = 20 each). Cyclic fatigue was tested using artificial canals that were milled in stainless steel blocks using a laser micromachining technique. The canals had a curvature angle of 60 and a curvature radius of 5 mm. The center of maximum curvature was set at 5 mm from the instrument tip. The block of artificial canals was stabilized inside a container that was filled with one of the tested solutions. The temperature was fixed at 37 °C with a tolerance limit of 1 °C. The number of cycles to fracture (NCF) was calculated and the fractured surfaces were examined using a scanning electron microscope. All statistical analyses were performed using SPSS software Version 20 (IBM-SPSS Inc., Chicago, IL) at a confidence level of 95%. RESULTS: ETP showed higher NCF than PTG in any of the tested solutions (P < 0.05). Within each group, NaOCl drastically decreased the NCF compared to water and EDTA (P < 0.05) and changing the solution from distilled water to EDTA did not affect the fatigue resistance (P > 0.05). CONCLUSIONS: ETP showed improved cyclic fatigue performance compared to PTG in all tested irrigating solutions. EDTA can be used in combination with NiTi instruments during canal instrumentation without compromising the cyclic fatigue resistance of PTG and ETP instruments. However, NaOCl drastically decreased the NCF.

Clinical dental students' knowledge regarding proper dental settings for treating patient during COVID-19: A cross-sectional study.

OBJECTIVES: To investigate the clinical dental students' knowledge on the proper dental setting during COVID-19. METHODS: Using multicenter cross-sectional study, a 10-items questionnaire was distributed in April 2020 among senior dental students from two dental schools. It comprised three main domains: demographic questions, questions investigating student's access to the proper recommendations of dental settings during COVID-19 and the specific recommendations questions. RESULTS: The questionnaire was sent to 654 clinical dental students and the total number of respondents were 267 representing a response rate of 40.83%. The overall knowledge mean was low (1±0.92). Gender was not a statistically significant factor affecting the knowledge score (P > 0.05). Most of the participants never visited the Saudi Center for Disease Prevention and Control (Saudi CDC) website and received no guidance or advice regarding proper dental practices during COVID-19. A statistically significant relationship was observed between the mean knowledge score and access to knowledge variables (P < 0.05). CONCLUSION: It was noted that clinical dental students have low knowledge on the proper dental settings during COVID-19 pandemic that was recommended by the Saudi CDC guidelines and they must be equipped with adequate knowledge from reliable sources to overcome their insufficiencies such as a well-structured and dynamic curriculum.

A micro-computed tomographic evaluation of retreatability of BioRoot RCS in comparison with AH Plus.

This study compared the retreatability of filling material from canals filled with BioRoot RCS (Septodont, Saint-Maur-des-Fosses, France) and AH Plus (Dentsply DeTrey, Konstanz, Germany) combined with gutta-percha using micro-computed tomography for evaluation. Thirty-four mandibular premolars were divided into two groups according to the sealer used. Thirty days after obturation, canals were retreated with a ProTaper Universal retreatment system (Dentsply Maillefer, Ballaigues, Switzerland) followed by passive ultrasonic irrigation (PUI). The time taken for retreatment was recorded. The roots were scanned after obturation, after retreatment and after PUI. Data were analysed using the Mann-Whitney and Wilcoxon tests. Canals filled with BioRoot RCS exhibited significantly less remaining filling material than canals filled with AH Plus (P < 0.05). The addition of PUI resulted in a significant decrease in the residual material in both groups (P < 0.05). A significantly shorter retreatment time was reported for the AH Plus group than the BioRoot RCS group (P < 0.05).

The effect of intracanal medicaments used in Endodontics on the dislocation resistance of two calcium silicate-based filling materials.

BACKGROUND: Intracanal medicaments can be used in various endodontic conditions including multiple visit endodontics after trauma or in regenerative endodontics. These medicaments should be removed from the root canal before the placement of the filling or repair material. The aim of the present study was to evaluate the effect of prior calcium hydroxide (Ca(OH)2) and modified triple antibiotic paste (mTAP) placement on the push-out bond strength of TotalFill BC fast set putty (BC fast set putty) to root dentin when compared to mineral trioxide aggregate (MTA). METHODS: The root canals of 45 extracted mandibular premolars were prepared to a standardized internal diameter (1.5 mm). The specimens were randomly assigned to 3 groups according to the intracanal medicament used: mTAP (a mixture of metronidazole, ciprofloxacin, and cefaclor), Ca(OH)2, and no intracanal medicament. After 1 week, the medicaments were removed, and the middle third of the roots were cut into two transverse sections (2.0 ± 0.05) (n = 90 slices). Thereafter, the specimens were divided into two subgroups (n = 45 each): MTA or BC putty. After 1 week, the push-out test was performed and failure mode was evaluated. The data were statistically analyzed using two-way ANOVA and Tukey's post hoc. RESULTS: The application of the intracanal medicament did not significantly affect the bond strength of BC putty (p > .05). For MTA, the prior application of Ca(OH)2 or mTAP significantly decreased the dislocation resistance (p < .05). Specimens in the MTA subgroups showed an almost equal number of cohesive and mixed types of failure while the majority of the specimens in the BC putty subgroups revealed the cohesive type. CONCLUSIONS: Ca(OH)2 and mTAP promoted lower bond strength of MTA to root dentin compared to the control group. However, the BC fast set putty bond strength to dentin was not affected by prior medication with Ca(OH)2 or mTAP.

Torsional resistance of three ProTaper rotary systems.

BACKGROUND: The aim of this study is to compare the torsional resistance of the available ProTaper rotary systems, namely, ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG). METHODS: A total of 195 files from the three systems distributed into 13 groups (PTU-S1, PTU-S2, PTU-F1, PTU-F2, PTU-F3, PTG-S1, PTG-S2, PTG-F1, PTG-F2, PTG-F3, PTN-X1, PTN-X2 and PTN-X3) were subjected to torsional fatigue until failure. The torsional test was performed according to ISO 3630-1, where each file was placed in a straight position to eliminate the influence of cyclic fatigue. The Kruskal-Wallis test was conducted to compare the mean maximum torques and angular deflections at fracture for the groups, and the Mann-Whitney test was performed for pairwise comparisons. The significance level was set at 0.05 and the fractured surfaces were examined under a scanning electron microscope. RESULT: Among the tested files, PTG-S1 had the lowest torsional fatigue resistance, whereas PTU-F2 and PTU-F3 had the highest torsional resistance. The scanning electron microscope showed typical features of torsional failure. CONCLUSION: The new ProTaper systems (PTG and PTN) did not show improved torsional resistance in comparison with PTU.

Cyclic Fatigue and Torsional Failure of EdgeTaper Platinum Endodontic Files at Simulated Body Temperature.

INTRODUCTION: The aim of this in vitro study was to compare the cyclic fatigue resistance and torsional resistance of EdgeTaper Platinum (ETP) with those of ProTaper Gold (PTG) at simulated body temperature. METHODS: ETP and PTG files with #25 tip size were selected. Cyclic fatigue tests were performed in a stainless steel artificial canal until file fracture occurred. The time to fracture was recorded. For the torsional resistance testing, the apical 5 mm of the file was firmly secured with acrylic resin, and the assembly was fixed over torque gauge device. A uniform torsional stress was applied with continuous rotation motion until fracture occurred. The torque at failure was recorded. Both experiments were conducted at 35 ± 1°C. Fractured surfaces were tested via scanning electron microscopy. Statistical analysis was performed using independent Student t test at 5% significance level. RESULTS: The ETP had superior cyclic fatigue resistance than PTG (P < .01). However, it exhibited lower torsional resistance (P < .05). The ETP and PTG showed typical features of cyclic and torsional fatigue behavior under scanning electron microscopy. CONCLUSIONS: The ETP exhibited superior resistance to cyclic fatigue but failed to show any improvement in the torsional resistance compared with PTG.

Non-Invasive management of invasive cervical resorption associated with periodontal pocket: A case report.

BACKGROUND: Invasive cervical resorption (ICR), a commonly misdiagnosed condition, is an aggressive form of external tooth resorption that contributes to periodontal tissue inflammation and deepening of the periodontal pockets. Herein we report the case of a patient, exhibiting ICR and elaborate the effects of a non-surgical approach in the amelioration of this condition. CASE SUMMARY: A 21-year-old female reporting intermittent pain at the upper left side, multiple restorations, no trauma history, and having received orthodontic treatment was studied. Localized erythematous swelling was noted at the buccal interdental papilla between the left maxillary first molar and second premolar. The diseased pulp and tissue in resorption were removed and the root canal system including the defect were sealed using gutta percha/AH Plus and mineral trioxide aggregate (MTA). At the one-year recall, the tooth showed no symptoms and responded normally to percussion and palpation. The surrounding periodontium exhibited a normal color and the probing depth was normal. Radiographic examination showed a restoration of crestal alveolar bone and good adaption to MTA. CONCLUSION: Non-surgical root canal treatment in conjunction with resorption defect orthograde repair with MTA was found to be an effective treatment option in the elimination of ICR. Early diagnoses are recommended in order to employ non-surgical approaches for management of ICR instead of surgical interventions.

Evaluation of root canal morphology of mandibular premolars in a Saudi population using cone beam computed tomography: A retrospective study.

OBJECTIVE: To investigate the root canal morphology of mandibular first and second premolars using Cone-Beam Computed Tomography (CBCT) in a Saudi population. METHODS: CBCT images of 707 patients, number of roots and canal configuration were identified and categorized according to Vertucci classification. Bilateral symmetry and association between gender and number of roots, as well as gender and root canal configuration were investigated. RESULTS: Majority of the patients had one root and type I root canal configuration in mandibular first (96.4%) and second premolar (95.6%). All types of canal configurations were observed except Type VII for the mandibular first premolar, and Types VI and VII for the mandibular second premolar. High degree of bilateral symmetry was seen in both mandibular first and second premolars in terms of the number of roots and canal configuration; 93.8% and 97.8%, respectively. There was an association between gender and number of roots (P = 0.04) and gender and root canal configuration in mandibular first premolar (P = 0.030). CONCLUSIONS: Single-root with type I canal configuration was the most prevalent of mandibular premolars in the Saudi population. However, incidence of more than one root with different canal configurations was detected.

Prevalence of C-shaped canal system in mandibular first and second molars in a Saudi population assessed via cone beam computed tomography: a retrospective study.

OBJECTIVES: The purpose of this study was to determine the prevalence of the C-shaped root canal configuration, location of the longitudinal groove, sex differences, and unilateral/bilateral presence in mandibular first and second molars in a Saudi population using cone beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT images for the mandibular first and second molars of 487 patients (a total of 529 first molars and 681 s molars) were evaluated. The teeth were assessed for the presence of C-shaped root canals according to Fan criteria. Subdivisions were also made according to sex, direction of the longitudinal groove, and unilateral/bilateral presence. RESULTS: Only one C-shaped mandibular first molar was observed (0.19%), whereas 62 second molars (9.1%) exhibited C-shaped anatomy. Unilateral presence of the C-shaped root canal system was more common (53.85%). Female patients had a higher prevalence than males. Longitudinal grooves were most commonly found on the root lingual surface (58.1%). CONCLUSIONS: The prevalence of the C-shaped canal configuration in a Saudi Arabian population was 0.19% in the mandibular first molar and 9.1% in the mandibular second molar. Longitudinal groove prevalence was highest on the lingual surface. Women had a significantly higher prevalence of the C-shaped canal configuration than men. Patients with unilateral presence of the C-shaped canal configuration were more common than those with bilateral presence. CLINICAL RELEVANCE: Tooth type, patient sex, and ethnicity can help clinicians predict the prevalence of the C-shaped canal system in mandibular molars.

Cone-Beam Computed Tomographic Evaluation of Root Canal Morphology of Maxillary Premolars in a Saudi Population.

OBJECTIVE: The aim of the study was to investigate the root canal morphology of maxillary first and second premolars in a Saudi population using Cone-Beam Computed Tomography (CBCT). METHODS: This retrospective cross-sectional study assessed CBCT images of 707 Saudi patients. The number of roots and canal configuration were identified based on Vertucci's classification. Fisher's exact Chi-square tests were performed to analyze the association between sex and number of roots and sex and root canal configuration. RESULTS: Most teeth had two roots in maxillary first premolars (75.1%) and one root in maxillary second premolars (85.2%). Type IV was the most prevalent canal configuration in maxillary first premolars (69.1%), while Type I was the most in maxillary second premolars (49.4%). All types of canal configurations were observed in maxillary premolars except Type VII for the maxillary second premolar. Chi-square tests showed no significant association between gender and number of roots and sex and root canal configuration in both maxillary first and second premolars although higher number of roots was seen in men (P > 0.05). CONCLUSION: Most maxillary first premolars had two roots with Type IV being the most predominant canal configuration, while a single root with Type I canal configuration was the most frequently observed morphology in maxillary second premolars. In maxillary first premolars, 21.3% had one canal apically, 75.4% had two canals apically, and 3.3% had three canals apically. In maxillary second premolars, 80.2% had one canal apically, 18.9% had two canals apically, and 0.9% had three canals apically.

Effects of Sodium Hypochlorite Concentration and Temperature on the Cyclic Fatigue Resistance of Heat-treated Nickel-titanium Rotary Instruments.

INTRODUCTION: We tested the cyclic fatigue resistance of heat-treated instruments immersed in sodium hypochlorite solution under different concentrations and temperature conditions. METHODS: Based on the irrigating solution's concentration and temperature, 135 ProTaper Gold (PTG; Dentsply Sirona, York, PA) F2 instruments were divided equally into 9 groups of 15. Cyclic fatigue testing was performed by using a block with artificial canals with a curvature angle of 60°, a curvature radius of 5 mm, and a curvature center 5 mm from the instrument tip. The block was fixed inside a water bath of distilled water, 2.5% sodium hypochlorite (NaOCl), or 5.25% NaOCl. The temperature was preset at 25°C, 37°C, or 60°C. The instrument was rotated at 300 rpm until fracturing occurred. The number of cycles to fracture was calculated, and the fragment length was measured. Fractured surfaces were examined via scanning electron microscopy. NCF data were analyzed statistically via Kruskal-Wallis and Mann-Whitney tests. All statistical analyses were performed using SPSS software Version 22 (IBM Corp, Armonk, NY) at a 5% significance level. RESULTS: The number of cycles to fracture of the PTG F2 was highest in distilled water at 25°C and lowest in 5.25% NaOCl at 60°C. Changing the irrigating solution from distilled water to NaOCl and increasing the surrounding temperature reduced the fatigue resistance. CONCLUSIONS: NaOCl irrigating solution at different concentrations and temperatures influenced the cyclic fatigue resistance of PTG instruments. Future NiTi instrument failure studies should be conducted under simulated body temperature conditions in commonly used irrigating solutions.

Superfast Set, Strong and Less Degradable Mineral Trioxide Aggregate Cement.

PURPOSE: Despite the good sealing ability and biocompatibility of mineral trioxide aggregate (MTA), its slow setting, high degradation, and weakness limit its use in surgical endodontics and high stress-bearing areas. This study aimed to develop two new liquids to control these drawbacks. They were prepared from calcium chloride, fumed silica, and hydroxyapatite or calcium phosphate and coded "H" and "P," respectively. METHODS: Portland cement, Grey ProRoot® MTA, and white ProRoot MTA were mixed with distilled water (control) or liquid "H" or "P." The pH, setting time, degradation rate, leachant/precipitate' composition, compressive strength, and morphology were assessed. RESULTS: Both liquids maintained MTA's high alkalinity and reduced the setting time by 1-2 orders of magnitude. Both liquids, H in particular, significantly reduced the degradation rate of Grey ProRoot and White ProRoot MTA®. Calcite has been identified as the main phase of the leachant or precipitate formed during the cement's degradation. Calcium hydroxide or hydroxyapatite was also identified with Grey ProRoot MTA mixed with H liquid. These liquids also significantly increased the compressive strength with no statistical differences between them; this was associated with the production of dense, consolidated structures. CONCLUSIONS: The modified MTA could be used in surgical endodontics and high stress-bearing areas.